Detachable implantable devices

ABSTRACT

In some aspects, the present disclosure provides a delivery device for delivering a detachable medical implant that comprises an elongated delivery member and a first engagement portion. The first engagement portion comprises a first proximal-facing surface, a first distal-facing surface, and a first lumen that is configured to accommodate an activation wire, wherein at least 50% of a surface area of the first proximal-facing surface is angled away from a proximal end of the first engagement portion. In other aspects, the present disclosure provides a medical delivery system comprising: such a delivery device; an implantable device comprising a medical device portion and a second engagement portion, the second engagement portion comprising a second lumen configured to accommodate an activation wire, a second proximal-facing surface and a second distal-facing surface; and an activation wire. Other aspects pertain to methods of medical device delivery using such a medical delivery system.

RELATED APPLICATION INFORMATION

This application is a continuation of U.S. patent application Ser. No.15/015,858, filed on Feb. 4, 2016, which claims the benefit of priorityunder 35 U.S.C. § 119 to U.S. Provisional Patent Application No.62/112,299, filed on Feb. 5, 2015, which is incorporated by reference inits entirety.

BACKGROUND

The endovascular treatment of a variety of conditions throughout thebody is an increasingly more important form of therapy. One suchprocedure uses embolization coils to occlude a target site by forming aphysical barrier to blood flow and/or by promoting thrombus formation atthe site. Such treatments can be useful where it is desired to reducevascularization, including treatments for aneurisms and cancer.

Coils have typically been placed at the desired site within thevasculature using a catheter and a delivery device such as a pushermember. As a first step, a flexible, small diameter catheter can beguided to the target site through the use of a guidewire or by othermeans. Once the site has been reached, the catheter lumen is cleared byremoving the guidewire (if a guidewire has been used), and the coil isplaced into the proximal open end of the catheter and advanced throughthe catheter via the delivery device, which has a distal end that isadapted to engage and push the coil through the catheter lumen as thedelivery device is advanced through the catheter. When the coil reachesthe distal end of the catheter, it is discharged from the catheter bythe delivery device into the vascular site.

Several techniques have been developed to enable more accurate placementof coils within a vessel, including techniques where the delivery deviceis temporarily affixed to the coil, and which can be released viaelectrical (e.g., electrolytic dissolution) and mechanical means (e.g.,interlocking members operated by an activation wire).

The present disclosure pertains to improved devices, systems and methodsfor implantable device delivery.

SUMMARY

In accordance some aspects, the present disclosure provides a deliverydevice for delivering a detachable medical implant that comprises anelongated delivery member and a first engagement portion. The firstengagement portion comprises a first proximal-facing surface, a firstdistal-facing surface, and a first lumen that is configured toaccommodate an activation wire, wherein at least 50% (in someembodiments, at least 75%, at least 90%, at least 95%, or more) of asurface area of the first proximal-facing surface is angled away from(e.g., relative to an imaginary plane oriented normal to an axis of thefirst lumen) a proximal end of the first engagement portion. Forexample, at least 50%, at least 75%, at least 90%, at least 95%, ormore, of the surface area of the first proximal-facing surface may curveaway from (e.g., relative to an imaginary plane oriented normal to anaxis of the first lumen) the proximal end of the first engagementportion as one moves toward an outer edge of the first proximal-facingsurface. As another example, at least 50%, at least 75%, at least 90%,at least 95%, or more, of the surface area of the first proximal-facingsurface may slope away from (e.g., relative to an imaginary planeoriented normal to an axis of the first lumen) the proximal end of thefirst engagement portion in a linear fashion, as one moves toward anouter edge of the first proximal-facing surface.

In various embodiments, which may be used in combination with the aboveaspects, at least 50% of the surface area of the first proximal-facingsurface is curved. For example, the first proximal-facing surface maycomprise a portion of a spheroidal surface. In certain cases, the firstengagement portion may comprise a spheroid or a portion of a spheroid,within which is formed the first lumen and which provides the firstproximal-facing surface and the first distal-facing surface. In thesecases, for example, (a) the elongated delivery member may be attached toa portion of a circumference of the spheroid and a plane passing throughthe circumference may be normal to an axis of the first lumen and/or (b)at least a portion of a length of the elongated member may comprise afirst longitudinally sliced portion of a first hollow cylinder and thespheroid may be disposed in a concave side of the first longitudinallysliced portion.

In various embodiments, which may be used in combination with the aboveaspects and embodiments, the engagement portion may comprise a portionof a hollow cylinder.

In various embodiments, which may be used in combination with any of theabove aspects and embodiments, the elongated delivery member may be atubular delivery member that is adapted to receive the activation wire.

In accordance other aspects, the present disclosure provides a medicaldelivery system comprising: (a) a delivery device in accordance with anyof the above aspects and embodiments, (b) an implantable devicecomprising a medical device portion and a second engagement portion, thesecond engagement portion comprising a second lumen, a secondproximal-facing surface and a second distal-facing surface, and (c) anactivation wire. In these aspects, the activation wire is configured (i)to simultaneous occupy the first and second lumens thereby holding thefirst and second engagement portions in the coupled state, and (ii) tobe removed from the first and second lumens thereby releasing the firstand second engagement portions from the coupled state. Typically, whenin the coupled state, the first distal-facing surface engages the secondproximal-facing surface when the medical device is pushed distally bythe elongated delivery member and the first proximal-facing surfaceengages the second distal-facing surface when the medical device ispulled proximally by the elongated delivery member.

In various embodiments, which may be used in combination with the aboveaspects and embodiments, the second engagement portion may comprise aspheroid or a portion of a spheroid, within which is formed the secondlumen and which provides the second distal-facing surface. In certain ofthese embodiments, the medical device may comprise a secondlongitudinally sliced portion of a second hollow cylinder, the spheroidmay be disposed in a concave side of the second longitudinally slicedportion, a proximal end of the medical device portion may also bedisposed in the concave side of the second longitudinally slicedportion, and the spheroid may be longitudinally spaced from the medicaldevice portion by a gap within which the first engagement portion ispositioned when the first and second engagement portions are in thecoupled state.

In various embodiments, which may be used in combination with the aboveaspects and embodiments, the first and second engagement portions maycomprise complementary surfaces. In certain of these embodiments, thefirst and second engagement portion may form a hollow cylinder when inthe coupled state.

In various embodiments, which may be used in combination with the aboveaspects and embodiments, the medical device portion may comprise avascular occlusion device (e.g., an embolic coil, etc.).

In accordance yet other aspects, the present disclosure provides amethod of implanting an implantable device in a subject comprising (a)inserting a medical system in accordance with any of the above aspectsand embodiments into a subject when in the coupled state and (b)withdrawing the activation wire from the first and second lumens suchthat the implantable device is released in the subject.

An advantage associated with delivery devices described herein is thatthey are resistant to engagement with (e.g., snagging) tissue or apreviously implanted device upon removal of the delivery devices from asubject.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic illustration of a distal portion of a deliverydevice and a proximal portion of an implantable device in accordancewith an embodiment of the present disclosure.

FIG. 1B is a schematic illustration of a delivery system wherein thedelivery device and implantable device shown in FIG. 1A are coupled andheld together via an actuation wire.

FIG. 1C is a schematic illustration of a portion of the implantabledevice of FIG. 1A.

FIG. 2A is a schematic illustration of a distal portion of a deliverydevice in accordance with an embodiment of the present disclosure.

FIG. 2B is a schematic illustration of a proximal portion of a deliverydevice in accordance with an embodiment of the present disclosure.

FIG. 2C is a schematic illustration of a delivery system wherein thedelivery device of FIG. 2A and the implantable device of FIG. 2B arecoupled and held together via an actuation wire.

DETAILED DESCRIPTION

A more complete understanding of the present disclosure is available byreference to the following detailed description of numerous aspects andembodiments of the disclosure. The detailed description which follows isintended to illustrate but not limit the disclosure.

As used herein, the terms “proximal” and “distal” generally refer to therelative position, orientation, or direction of an element or action,from the perspective of a clinician using the medical device, relativeto one another. Thus, “proximal” may generally be considered closer tothe clinician or an exterior of a patient, and “distal” may generally beconsidered to be farther away from the clinician, along the length orbeyond the end of the medical device.

Disclosed herein are delivery devices, systems and methods fordelivering an implantable device to a target site, in particular, adetachable, implantable device. The systems include a delivery deviceand implantable device which can be held in a coupled arrangement byinsertion of an activation wire and released from one another by removalof the activation wire. Discussed below are a variety of couplingconfigurations which include features adapted to inhibit unwantedinteraction between the delivery device and the delivery environment(including tissue, previously placed devices, etc.) when retracting thedelivery device after delivery.

In accordance with various aspects of the present disclosure, deliverydevices are provided which comprise (a) an elongated delivery member,for example, an elongated tube or elongated rod (e.g., a stiff wire),and (b) an engagement portion having a proximal end and a distal end andcomprising a lumen that is configured to accommodate an activation wire.The engagement portion also comprises a proximal-facing surface and adistal-facing surface, wherein at least 50% of the proximal-facingsurface area of the engagement portion is angled away from the proximalend of the engagement portion. For example, at least 50%, at least 60%,at least 70%, at least 80%, at least 90%, at least 95%, or more, of theproximal-facing surface area of the engagement portion may be angledaway from the proximal end of the engagement portion. This feature isadvantageous, for example, in that when the delivery device isultimately withdrawn proximally after delivery of the implantabledevice, is resistant to engagement with another object (e.g., tissue, apreviously implanted device, etc.).

In certain embodiments, at least 50% of the proximal-facing surface areaof the first engagement portion is curved. For example, at least 50%, atleast 60%, at least 70%, at least 80%, at least 90%, at least 95%, ormore, of the proximal-facing surface area of the engagement portion maybe curved.

In accordance with various aspects of the present disclosure, medicalsystems are provided which comprise a delivery device, an implantabledevice and an activation wire configured to reversibly couple theimplantable device and delivery device together. The delivery devicecomprises an elongated delivery member, for example, an elongated tubeor elongated rod, and a first engagement portion having a proximal endand a distal end and comprising a first lumen, a first proximal-facingsurface and a first distal-facing surface, wherein at least 50% of theproximal-facing surface area of the first engagement portion is angledaway from the proximal end of the first engagement portion. For example,at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, atleast 95%, or more, of the proximal-facing surface area of the firstengagement portion may be angled away from the proximal end of the firstengagement portion. The implantable device includes a medical deviceportion (e.g., an occlusion device such as an embolization coil, etc.)and a second engagement portion comprising a second lumen, a secondproximal-facing surface and a second distal-facing surface.

Moreover, the first and second engagement members may be configured toform a coupled state in which the first and second lumens are aligned,in which at least one first distal-facing surface of the firstengagement portion engages at least one second proximal-facing surfaceengagement portion when the medical device is pushed distally by theelongated delivery member, and in which at least one firstproximal-facing surface of the first engagement portion engages at leastone second distal-facing surface of the second engagement portion whenthe medical device is pulled proximally by the elongated deliverymember.

Prior to delivery of the implantable device, the first and secondengagement portions are bought together and the activation wire issimultaneously disposed within the first and second lumens of the firstand second engagement portions, forming a delivery system in which thedevices are reversibly coupled, with decoupling being accomplished bywithdrawal of the activation wire. Thus, the activation wire isconfigured to simultaneous occupy the first and second lumens and holdthe first and second engagement portions in the coupled state duringdelivery and is further configured to be removed from the first andsecond lumens and release the first and second engagement portions fromthe coupled state.

In one embodiment, such a delivery system be employed to place one ormore coils or other implantable device(s) at a target site within thevasculature using a flexible, small diameter catheter. As a first step,the catheter can be guided to the target site through the use of aguidewire or by other means. Once the site has been reached, thecatheter lumen is cleared by removing the guidewire (if a guidewire hasbeen used) and the distal end of the system (i.e., the distal end of themedical device portion, e.g., the distal end of a coil) is placed into aproximal open end of the catheter and advanced through the catheter viathe delivery member. Once the implantable device emerges from the distalend of the catheter and is positioned at the desired target site, theactivation wire may be withdrawn, allowing the first and secondengagement portions to disengage, thereby releasing the medical deviceat the vascular site. Because the first engagement portion describedherein is designed such that essentially all of the proximal-facingsurface area of the first engagement portion is angled away from theproximal end of the first engagement portion, withdrawal of the firstengagement portion from the vasculature and into the catheter isfacilitated.

In certain embodiments, the medical device portion may comprise avascular occlusion device, such as an embolic coil or other occlusiondevice. Where the medical device portion is an embolic coil, it may beformed from metals or alloys, for example, selected from platinum groupmetals, particularly platinum, rhodium, palladium, and rhenium, as wellas tungsten, gold, silver, tantalum, and alloys of these metalsincluding platinum/tungsten alloy. These materials have significantradiopacity, and their alloys may be tailored to have a blend offlexibility and stiffness for the coil. They are also generallybiologically inert. The coil may also include shape memory components,such as nitinol components, among others.

In certain embodiments, the elongated delivery member may be a solidelongated member (e.g., a solid rod, also referred to herein as a wire)or may be a tubular delivery member having a lumen. Where the elongateddelivery member is a tubular delivery member, the lumen may be adaptedto receive the activation wire.

The elongated delivery member may be made using a variety ofbiocompatible materials. Beneficial materials for forming the elongateddelivery member include metals (including pure metals and metal alloys),for example, selected from stainless steel (e.g., 303, 304v, or 316Lstainless steel), nickel-titanium alloy (nitinol) (e.g., super elasticor linear elastic nitinol), nickel-chromium alloy, nickel-chromium-ironalloy, cobalt alloy, nickel, titanium, platinum, and the like.Beneficial materials for forming the elongated delivery member furtherinclude stiff polymers such as polycarbonates, polyamides (e.g., nylons,etc.), parylene coatings or layers, and the like. In some embodiments,the elongated delivery member may be formed from a combination ofpolymeric and inorganic (e.g., metals, ceramics, etc.) materials.

The engagement portions may also be made using a variety ofbiocompatible materials. Beneficial materials for forming the engagementportions include those materials listed above for forming the elongateddelivery member, among others.

It will be appreciated that the various components of the disclosureincluding the engagement portions can be formed from or may include aradiopaque material. One skilled in the art will appreciate that avariety of imaging capable materials can be used, including, forexample, materials detectable with, x-ray, including fluoroscopy, MRI,CT, PET, SPECT, and combinations thereof.

In certain embodiments, the first and second engagement portions maycomprise complementary surfaces. In certain embodiments, the first andsecond engagement portions may each comprise a portion of a hollowcylinder and may have complementary surfaces that engage one another toform a hollow cylinder.

One embodiment of the disclosure will now be described in conjunctionwith FIGS. 1A-1C. Turning to FIG. 1A, there is schematically illustratedtherein a distal portion of a delivery device 108 and a proximal portionof an implantable device 106.

The delivery device 108 comprises an elongated delivery member 112,specifically, an elongated tubular delivery member. The delivery device108 also comprises a first engagement portion 110 comprising a lumen 110a, at least one first proximal-facing surface (specifically two firstproximal-facing surfaces 110 p 1, 110 p 2) and at least one firstdistal-facing surface (specifically two first distal-facing surfaces 110d 1, 110 d 2). As can be seen substantially all of the proximal-facingsurface area (i.e., the combined surface area of 110 p 1 and 110 p 2) ofthe first engagement portion 110 is angled away from the proximal end(i.e., angled toward the end that is opposite the delivery device 108)of the first engagement portion 110. As previously noted, this isadvantageous in that, when the delivery device 108 is ultimatelywithdrawn proximally after delivery of the implantable device, it isless likely to engage another object (e.g., tissue or a previouslyimplanted device). As also can be seen substantially all of theproximal-facing surface area is curved. The surfaces 110 p 1, 110 p 2,110 d 1, 110 d 2 are provided by first engagement member 116 in theembodiment shown.

The implantable device 106 includes a medical device portion 102, inparticular, an occlusion device such as an embolization coil (only aproximal portion of the embolization coil is illustrated) having a coillumen 102 a and a second engagement portion 104, which is complementaryto the first engagement portion 110. Seen in FIGS. 1A and 1C, like thefirst engagement portion 110, the second engagement portion 104comprises at least one second distal-facing surface (specifically, twosecond distal-facing surface 104 d 1, 104 d 2) and at least one secondproximal-facing surface (specifically, two second proximal-facingsurfaces 104 p 1, 104 p 2). The second engagement portion 104 alsocomprises a lumen 104 a. The lumen 104 a and surfaces 104 p 1, 104 p 2,104 d 1, 104 d 2 are provided by a second engagement member 114, whichis shown separately in FIG. 1C. Although the second engagement member114 is essentially a mirror image of the first engagement member 116,this is not required, as a wide variety of asymmetric configurationspossible.

Prior to delivery, the first and second engagement portions 110, 104 arebought together as shown in FIG. 1B and an activation wire 109 (aportion of which is shown in phantom) is simultaneously positionedwithin the first and second lumens 110 a, 104 a such that the devicesare reversibly coupled. In particular, in the embodiment shown, theactivation wire 109 simultaneously occupies a lumen of the delivery tube112, the first engagement portion lumen 110 a, the second engagementportion lumen 104 a, and a portion of the coil lumen 102 a (this isoptional as it is not necessary for coupling). Because the firstengagement portion 110 has at least one proximal-facing surface (i.e.,110 p 1, 110 p 2) that can engage at least one distal-facing surface(i.e., 104 d 1, 104 d 2) of the second engagement portion 104, when theelongated delivery member 112 of the delivery device 108 is pulled in aproximal direction, the first engagement portion 110 will engage andpull the second engagement portion 104 in a proximal direction.Analogously, because the first engagement portion 110 has at least onedistal-facing surface (i.e., 110 d 1, 110 d 2) that can engage at leastone proximal-facing surface (i.e., 104 p 1, 104 p 2) of the secondengagement portion 104, when the elongated delivery member 112 of thedelivery device 108 is pushed in a distal direction, the firstengagement portion 110 will engage and push the second engagementportion 104 in a distal direction. It should be noted that while thefirst and second engagement portions 110, 104, have two pairs ofsurfaces that can potentially engage when the delivery device 108 ispushed in a distal direction and pulled in a proximal direction, onepair of surfaces is sufficient for each direction.

It should also be noted that the coil 102 and second engagement member114 may be formed from a single piece of material or from differentpieces of material. Similarly, the elongated delivery member 112 andfirst engagement member 116 may be formed from a single piece ofmaterial or from different pieces of material. In this regard, variousmaterials described herein may be attached using a variety of suitabletechniques, for example, soldering, welding, adhering (e.g., withadhesive), and/or mechanically mating the materials together.

Once the first and second engagement portions 110, 104 are paired asshown in FIG. 1C and the activation wire 109 is introduced through thelumens 110 a and 104 a of the first and second engagement portions 110,104, then first and second engagement portions 110, 104 will remainedcoupled until the activation wire 109 is removed, at which point thefirst and second engagement portions 110, 104 are released from oneanother.

As will be appreciated by those skilled in the art upon viewing FIG. 1A,when the delivery tube 112 and first engagement member 116 are separateentities, the first engagement portion lumen 110 a may be provided byeither the distal end of the delivery tube 112 or the first engagementmember 116, or both. Similarly, when the second engagement member 116and coil 102 are separate entities, the second engagement portion lumen104 a may be provided by the second engagement member 116, a proximalportion of the coil 102, or both.

In the embodiments shown in FIGS. 1A-1C, first and second engagementmembers 116, 114 comprise complementary surfaces, and the first andsecond engagement members 116, 114 each comprise a portion of a hollowcylinder. Consequently, when the complementary surfaces of the first andsecond engagement members 116, 114 engage one another as shown in FIG.1B, a hollow cylinder is formed.

In one embodiment, a delivery system like that shown in FIG. 1B may beemployed to place the implantable device 106 at a target site within thevasculature using a catheter. Once the catheter has been guided to thedesired location in the vasculature, the distal end of the coil (notshown in FIG. 1B) is placed into a proximal open end of the catheter andadvanced through the catheter via the delivery member 112. Once theimplantable device 106 emerges from the distal end of the catheter andis positioned at the desired target site, the activation wire 109 can bewithdrawn, allowing the first engagement portion 110 to decouple fromthe second engagement portion 104, thereby releasing the medical device106 at the vascular site. Because the first engagement portion 110 isdesigned such that essentially all of the proximal-facing surface areaof the first engagement portion 110 is angled away from the proximal endof the first engagement portion 110, withdrawal of the first engagementportion from the vasculature and into the catheter is facilitated.

In various additional embodiments, the first engagement portion isprovided with a proximal-facing surface that may comprise, for example,a partial surface of a spheroid (e.g., a sphere, oblate spheroid,prolate spheroid, etc.). In some of these embodiments, the firstengagement portion may comprises a spheroid or a portion thereof (e.g.,a hemi-spheroid such as a hemisphere) wherein the spheroid or a portionthereof contains the first lumen of the first engagement portion. Asdiscuss in more detail below, the elongated delivery member may bedirectly or indirectly attached to a circumference of the spheroid.

Turning now to FIGS. 2A-2C, and in particular to FIGS. 2A and 2B, thereare schematically illustrated therein a distal portion of a deliverydevice 108 and a proximal portion of an implantable device 106,respectively. The distal portion of the delivery device 108 comprises afirst engagement portion 110 comprising a first lumen 110 a, a firstproximal-facing surface 110 p and a first distal-facing surface 110 d,wherein substantially all of the proximal-facing surface area of thefirst engagement portion 110 (i.e., corresponding to the area of firstproximal-facing surface 110 p) is angled away from the proximal end ofthe delivery device. In the example shown, the first proximal-facingsurface is a curved surface and, more particularly, is a portion of aspherical surface. A surface of this type is advantageous in that, whenthe delivery device 108 is ultimately withdrawn proximally afterdelivery of the implantable device, it is less likely to engage anotherobject (e.g., tissue or a previously implanted device). In theparticular embodiment shown, the first lumen 110 a and surfaces 110 p,110 d are provided by a first engagement member 116, which is in theform of a sphere having a lumen 110 a with an axis 116 a. FIG. 2A alsoincludes an attachment member 107 that is attached to the firstengagement member 116 and is discussed in more detail below.

The implantable device 106 includes a medical device portion, forexample, an occlusion device such as an embolization coil 102 having acoil lumen (only a proximal portion of the embolization coil isillustrated) and a second engagement portion 104 comprising a secondlumen 104 a, at least one second distal-facing surface 104 d and atleast one second proximal-facing surface 104 p. The second lumen 104 aand the second distal-facing surface 104 d are provided by a secondengagement member 114, which is in the shape of a sphere having a lumenformed therein. The second proximal-facing surface 104 p is provided bycoil 102. The second engagement member 114 and coil 102 are held a fixeddistance apart by spacing member 105, forming a gap 105 g.

Prior to delivery, first and second engagement portions 110, 104 arebought together as shown in FIG. 2C. (It is noted that the spacingmember 105 in the embodiment shown in FIG. 2C is longer than the spacingmember 105 in the embodiment shown in FIG. 2B.) Specifically, the firstengagement member 116 of the delivery device is introduced into the gap105 g of the implantable device. Beneficially, a width of the gap iswider than a diameter of first engagement member 116 by an amount thatis just sufficient to allow first engagement member 116 to be readilyreleased. Once the first and second engagement portions 110, 104 arebought together as shown, an activation wire 109 (a portion of which isshown in phantom) is simultaneously positioned within the first andsecond lumens 110 a, 104 a such that the delivery device and implantabledevice are reversibly coupled. In particular, the activation wire 109simultaneously occupies the first engagement portion lumen 110 a, thesecond engagement portion lumen 104 a, and a portion of a coil lumen 102a (although not required for coupling). Because the first engagementportion 110 has at least one proximal-facing surface 110 p that faces atleast one distal-facing surface 104 d of the second engagement portion104, when the delivery device 108 is pulled in a proximal direction, thefirst engagement portion 110 will engage and pull the second engagementportion 104 in a proximal direction. Analogously, because the firstengagement portion 110 has at least one distal-facing surface 110 d thatfaces at least one proximal-facing surface 104 p of the secondengagement portion 104, when the delivery device 108 is pushed in aproximal direction, the first engagement portion 110 will engage andpush the second engagement portion 104 in a proximal direction.

Once the first and second engagement portions 110, 104 are paired asshown in FIG. 2C and the activation wire 109 is introduced through thelumens 110 a and 104 a of the first and second engagement portions 110,104, then first and second engagement portions 110, 104 will remainedcoupled until the activation wire 109 is removed, at which point thefirst and second engagement portions 110, 104 are released from oneanother.

As will be appreciated by those of ordinary skill in the art uponviewing FIGS. 2A-2C, the attachment member 107 is beneficially attachedalong portion of a circumference of the first engagement member 116 thatlies on a plane that is normal to axis 116 a so as to allow the firstengagement member 116 to be introduced into gap 105 g withoutinterference from the attachment member 107. The attachment member 107shown comprises a section of a hollow cylinder, for example, which maycorrespond to a distal portion of a tubular delivery member from whichmaterial has been cut away, or which may be attached to a separateelongated delivery member (not shown). Moreover, many other geometriesmay be employed for the attachment member. For example, the attachmentmember 107 may be in the form of a thin stiff wire (e.g. a curved orstraight ribbon-shaped wire, among others) in some embodiments. Inaddition, although the coil 102 provides the proximal-facing surface 104p of the second engagement portion 104 in the embodiment shown, aseparate engagement member may be provided for this purpose. Moreover,although the distal-facing surface 104 d of the second engagementportion 104 is provided by a second engagement member 114 in the shapeof a spheroid in the embodiment shown, second engagement members ofmyriad other geometries may be may be employed to provide thedistal-facing surface 104 d, so long as the geometry also allowsinsertion of the activation wire 116 and allows for release of the firstengagement portion 110. Furthermore, although the second lumen 104 a isprovided by the second engagement member 114, this function may beprovided by the coil 102 or an attachment thereto.

In one embodiment, a delivery system like that shown in FIG. 2C may beemployed to place the implantable device 106 at a target site within thevasculature using a catheter. Once the catheter has been guided to thedesired location in the vasculature, the distal end of the coil (notshown) may be placed into a proximal open end of the catheter andadvanced through the catheter via the delivery member. Once theimplantable device 106 emerges from the distal end of the catheter andis positioned at the desired target site, the activation wire 109 can bewithdrawn, allowing the first engagement portions 110 to decouple fromthe second engagement portion 104 to disengage, thereby releasing themedical device 106 at the vascular site. Because the first engagementportion 110 is designed such that essentially all of the proximal-facingsurface area of the first engagement portion 110 is angled away from theproximal end of the first engagement portion 110, withdrawal of thefirst engagement portion from the vasculature and into the catheter isfacilitated.

Although specific embodiments have been described with an embolic coilin the drawings, one of ordinary skill in the art will appreciate thatvariety of alternative medical devices could be substituted. Forexample, the systems described herein may be used to deliver a varietyof implantable devices in addition, or as an alternative, to the emboliccoil (e.g., scaffolding, therapeutic drugs, thrombogenic embolizingagents, etc.). Similarly, a variety of control devices for moving animplantable device through a lumen of a medical instrument may beemployed as a delivery member.

Still further, while the delivery system is generally described withrespect to the detachable device traveling through a catheter, oneskilled in the art will appreciate that the device may travel through avariety of medical instruments, such as, for example, introducers orendoscopes, and that the methods and devices describe herein are equallyapplicable to any medical device having a lumen for the delivery of adetachable, implantable device. In this regard, the term “catheter” asused herein can refer to the variety of medical devices having an innerlumen adapted for receiving a medical instrument and/or implantabledevice.

Still other embodiments of the disclosure will be apparent to thoseskilled in the art from consideration of the specification and practiceof the disclosure disclosed herein. It is intended that thespecification and examples be considered as exemplary only, with a truescope and spirit of the disclosure being indicated by the followingclaims.

What is claimed is:
 1. A delivery device for delivering a detachablemedical implant comprising: an elongated delivery member; an engagementportion at a distal end of the elongated delivery member; and a lumenextending through the engagement portion configured to accommodate anactivation wire; wherein the engagement portion includes an engagementsurface having a continuous curve extending substantially transverselyacross the lumen at an angle, the continuous curve extending to a crestand sloping distally.
 2. The device of claim 1, wherein the continuouscurve extends across the lumen at a plurality of locations along thelumen.
 3. The device of claim 1, wherein a first portion of thecontinuous curve proximal to the crest faces in a substantially proximaldirection and wherein a second portion of the continuous curve distal tothe crest faces in a substantially distal direction.
 4. The device ofclaim 1, wherein the elongated delivery member further comprises asubstantially cylindrical portion proximal to the engagement portion andabout the lumen.
 5. The device of claim 1, wherein the crest has aheight measured from an outer surface of the elongate delivery memberthat is less than a diameter of the elongate delivery member.
 6. Thedevice of claim 1, wherein the engagement surface extends across adiameter of the elongate delivery member.
 7. A medical delivery systemcomprising: a delivery device comprising: an elongated delivery member;a first engagement portion at a distal end of the elongated deliverymember having a first engagement surface with a continuous curveextending to a crest and continues sloping distally; and a first lumenextending through the first engagement portion; an implantable devicecomprising: a medical device portion; and a second engagement portion ata proximal end of the implantable device having a second engagementsurface with a continuous curve extending to a crest and continuessloping proximally, the second engagement surface configured to engagethe first engagement surface; an activation wire configured tosimultaneously occupy the first and second lumens.
 8. The system ofclaim 7, wherein a first portion of the first engagement surface that isproximal to the crest faces in a substantially proximal direction andwherein a second portion of the first engagement surface that is distalto the crest faces in a substantially distal direction.
 9. The system ofclaim 7, wherein the first engagement portion and the second engagementportion together form a substantially continuous outer surface whenengaged with each other.
 10. The system of claim 9, wherein thesubstantially continuous outer surface is a cylindrical shape.
 11. Thesystem of claim 7, wherein a portion of the first engagement portion isproximal to the second engagement portion when the first engagementportion is engaged with the second engagement portion.
 12. The system ofclaim 7, wherein the elongated delivery member further comprises asubstantially cylindrical portion proximal to the engagement portion andabout the first lumen.
 13. The system of claim 7, wherein the crest ofthe first engagement portion has a height less than a diameter of theelongate delivery member.
 14. The system of claim 7, wherein the firstengagement surface extends across a diameter of the elongate deliverymember.
 15. A delivery device for delivering a detachable medicalimplant comprising: an elongated delivery member having a longitudinalaxis; an engagement surface at a distal end of the elongated deliverymember having a continuous curve extending substantially transverselyacross the longitudinal axis at an angle to a crest and continuessloping distally; and a lumen extending through the engagement surfaceat at least three locations.
 16. The device of claim 15, wherein atleast one of the three locations is proximal to the crest and at leastone of the three locations is distal to the crest.
 17. The device ofclaim 15, wherein a first portion of the continuous curve proximal tothe crest faces in a substantially proximal direction and wherein secondportion of the continuous curve distal to the crest faces in asubstantially distal direction.
 18. The device of claim 15, wherein theelongated delivery member further comprises a substantially cylindricalportion proximal to the engagement portion and about the lumen.
 19. Thedevice of claim 15, wherein the crest has a height less than a diameterof the elongate delivery member.
 20. The device of claim 15, wherein theengagement surface extends across a diameter of the elongate deliverymember.